The invention relates to sawing machines and sawing plants for sectioning packs of panels of wood and/or of any like material, and more particularly relates to the double pressure beam of such machines, i.e., the member that presses a pack immediately upstream and downstream of the cutting line, parallelly thereto, in order to guarantee perfect cutting of the panels, without splinters.
The pressure beam in question is presently formed by two rectilinear parallel pressure elements, in the form of suitably shaped bars, which are associated with respective means for vertically guiding and moving them, so that the pressure beam can be adapted to different working requirements.
When changing the cutting program and/or the dimensions according to which packs of panels of a same or a different size are cut, the width or depth dimension of the leading and trailing side offcuts resulting from the perimetric trimming of said packs also changes. Such a change renders the operation of the double pressure beam problematic, since the pressure element located on the side of the offcut may operate on an offcut having a width or depth substantially equal to, or not much greater or smaller than, the distance between the inward face of the pressure element and the nearby cutting line. In this instance, anytime the pressure beam is lowered into its operative position, the pressure element comes to rub against the side of the pack, or it may bear on the offcut in such an anomalous position as to cause a defective cut by the cutting saw, or a violent drop of the pressure beam when the offcut is no more connected to the pack of panels from which it has been separated.
According to applicant's U.S. patent application Ser. No. 861,396, filed May 9, 1986, the vertical raising and lowering movement of the two pressure elements has been rendered independent, so that if the aforesaid event should occur, the pressure element which is on the side of the offcut can be kept in its lifted position. However, this solution does not solve the above disclosed problem, since, as disclosed in the aforementioned application, it is conveniently provided that when one pressure element does not contact the material in the course of being cut, it contacts the workpiece table on which the material is supported, so as to form a tunnel enclosing at its interior the path of the saw, for accident prevention reasons, and in order to make it possible to evacuate any dust resulting from the sawing operation, by means of a suction manifold operating in the longitudinal upper part of said tunnel. This arrangement is not always possible, since in some cases the width of the offcut strip is comprised within the critical limits which have been described above, i.e., is substantially equal to or not much greater or smaller than the distance between the inward face of the pressure element and the cutting line.
According to the present invention, there is provided a pressure beam in which the means for vertically guiding the pressure elements are associated with horizontal traverse means in such a manner that it is possible, when required, to cause at least the pressure element that is above the offcut of the pack of panels to change its lateral distance from the cutting line, so that it will correctly operate on the offcut, or will not interfere therewith, and will come into contact with the workpiece table of the sawing machine, thus guaranteeing in any case the closing of the aforesaid tunnel.